1. Field of the Invention
The present invention relates to a thermal transfer printer which is provided with a braking mechanism to apply tension to a ink ribbon.
2. Description of the Related Art
This kind of a thermal transfer printer comprises an ink ribbon supply section and an ink ribbon winding section onto which an ink ribbon sent from the ink ribbon supply is wound section after passing between a thermal head and a platen. Moreover, a braking mechanism is provided in the ink ribbon supply section which applies tension to the ink ribbon.
In some of conventional thermal transfer printers, the braking mechanism presses, for example, the ink ribbon supply shaft with a coiled spring to restrict the rotation and can also adjust stepwise the braking force applied to the ink ribbon supply shaft by stepwise compression or extending of the coiled spring for changing the spring force of the above spring.
Moreover, some conventional thermal transfer printers with a configuration in which a coiled spring fitted to an ink ribbon shaft is compressed or extended using a double nut provided at the tip of the above supply shaft have been known.
However, fine adjustment of the tension of the ink ribbon has not been able to be realized by the above configuration in which the coiled spring is compressed or extended stepwise. Moreover, loosening and fastening of a double nut has been troublesome in the above configuration in which the double nut is used. Furthermore, a certain degree of skill has been required for optimum adjustment operation in any conventional technologies, as there has bee no standard to judge to what degree the sprig pressure of the coiled spring has been adjusted.
Accordingly, the present invention has been made considering the circumstances described in the above chapter, it is an object of the present invention to execute high-precision and fine adjustment of the tension of the ink ribbon by simple operations.
A thermal transfer printer according to the present invention has a configuration comprising an ink ribbon supply section, an ink ribbon winding section onto which the ink ribbon sent from the ink ribbon supply section is wound after passing between a thermal head and a platen, and a braking mechanism which applies tension to the ink ribbon at the ink ribbon supply section.
The braking mechanism is configured to comprise: a first friction member which is fitted to a supply shaft to rotate and support the ink ribbon and is rotated as one body together with the supply shaft; a second friction member which is fitted to the supply shaft in such a way that relative rotation can be realized and for which absolute rotation at least in one direction is restricted and relative movement of the second friction member in the axial direction to the supply shaft can be realized; an operation member which is screwed into a screwed section formed on the supply shaft; and an energizing member which is arranged between the operation member and the second friction member and which presses the second friction member for energizing the second friction member.
The energizing member is configured to change energizing force for the second friction member by adjusting a screwed position of the operation member to the screwed section on the supply shaft.
The adjustment of the tension applied to the ink ribbon may be realized by only a simple operation in which the operation member is fixed and the supply shaft is pivoted. The above operation changes the screwed position of the operation member to the screwed section on the supply shaft to change the energizing force of the energizing member along the above change. Accordingly, the frictional force between friction members is changed to adjust the braking force of the supply shaft. Then, the tension applied to the ink ribbon which is installed on the supply shaft is adjusted.